+void os_exit(int exit_code) __attribute__((noreturn));
+
+/**
+ * Put tty into raw mode to mimic serial console better
+ */
+void os_tty_raw(int fd);
+
+/**
+ * Acquires some memory from the underlying os.
+ *
+ * \param length Number of bytes to be allocated
+ * \return Pointer to length bytes or NULL on error
+ */
+void *os_malloc(size_t length);
+
+/**
+ * Access to the usleep function of the os
+ *
+ * \param usec Time to sleep in micro seconds
+ */
+void os_usleep(unsigned long usec);
+
+/**
+ * Gets a monotonic increasing number of nano seconds from the OS
+ *
+ * \return A monotonic increasing time scaled in nano seconds
+ */
+u64 os_get_nsec(void);
+
+/**
+ * Parse arguments and update sandbox state.
+ *
+ * @param state Sandbox state to update
+ * @param argc Argument count
+ * @param argv Argument vector
+ * @return 0 if ok, and program should continue;
+ * 1 if ok, but program should stop;
+ * -1 on error: program should terminate.
+ */
+int os_parse_args(struct sandbox_state *state, int argc, char *argv[]);
+
+/*
+ * Types of directory entry that we support. See also os_dirent_typename in
+ * the C file.
+ */
+enum os_dirent_t {
+ OS_FILET_REG, /* Regular file */
+ OS_FILET_LNK, /* Symbolic link */
+ OS_FILET_DIR, /* Directory */
+ OS_FILET_UNKNOWN, /* Something else */
+
+ OS_FILET_COUNT,
+};
+
+/** A directory entry node, containing information about a single dirent */
+struct os_dirent_node {
+ struct os_dirent_node *next; /* Pointer to next node, or NULL */
+ ulong size; /* Size of file in bytes */
+ enum os_dirent_t type; /* Type of entry */
+ char name[0]; /* Name of entry */
+};
+
+/**
+ * Get a directionry listing
+ *
+ * This allocates and returns a linked list containing the directory listing.
+ *
+ * @param dirname Directory to examine
+ * @param headp Returns pointer to head of linked list, or NULL if none
+ * @return 0 if ok, -ve on error
+ */
+int os_dirent_ls(const char *dirname, struct os_dirent_node **headp);
+
+/**
+ * Get the name of a directory entry type
+ *
+ * @param type Type to cehck
+ * @return string containing the name of that type, or "???" if none/invalid
+ */
+const char *os_dirent_get_typename(enum os_dirent_t type);
+
+/**
+ * Get the size of a file
+ *
+ * @param fname Filename to check
+ * @return size of file, or -1 if an error ocurred
+ */
+ssize_t os_get_filesize(const char *fname);
+
+#endif